package com.huan.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;

public class Server {
    //定义属性
    private Selector selector;
    private ServerSocketChannel listenChannel;
    private static final int PORT = 6667;

    //构造器
    //初始化工作
    public Server() throws IOException {
        //得到选择器
        selector = Selector.open();
        //ServerSocketChannel
        listenChannel = ServerSocketChannel.open();
        //绑定端口
        listenChannel.socket().bind(new InetSocketAddress(PORT));
        //设置非阻塞模式
        listenChannel.configureBlocking(false);
        //将该listenChannel 注册到selector
        listenChannel.register(selector, SelectionKey.OP_ACCEPT);
    }

    //监听
    public void listen() {

        System.out.println("监听线程: " + Thread.currentThread().getName());
        try {

            //循环处理
            while (selector.select() > 0) {

                //遍历得到selectionKey 集合
                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                while (iterator.hasNext()) {
                    //取出selectionkey
                    SelectionKey key = iterator.next();
                    //监听到accept
                    if (key.isAcceptable()) {
                        SocketChannel sc = listenChannel.accept();
                        sc.configureBlocking(false);
                        //将该 sc 注册到seletor
                        sc.register(selector, SelectionKey.OP_READ);
                        //提示
                        System.out.println(sc.getRemoteAddress() + " 上线 ");
                    }else if (key.isReadable()) { //通道发送read事件，即通道是可读的状态
                        //处理读 (专门写方法..)
                        readData(key);
                    }
                    //当前的key 删除，防止重复处理
                    iterator.remove();
                }

            }
        } catch (Exception e) {
            e.printStackTrace();

        }
    }

    //读取客户端消息
    private void readData(SelectionKey key) {

        //取到关联的channle
        SocketChannel channel = null;

        try {
            //得到channel
            channel = (SocketChannel) key.channel();
            //创建buffer
            ByteBuffer buffer = ByteBuffer.allocate(1024);


            int count = channel.read(buffer);
            //根据count的值做处理
            if (count > 0) {
                //把缓存区的数据转成字符串
                byte[] bytes = new byte[buffer.position()];
                buffer.get(bytes);
                String msg = new String(bytes);
                //输出该消息
                System.out.println("form 客户端: " + msg);
                buffer.flip();
                //向其它的客户端转发消息(去掉自己), 专门写一个方法来处理
                sendInfoToOtherClients(msg, channel);
            }

        } catch (IOException e) {
            try {
                System.out.println(channel.getRemoteAddress() + " 离线了..");
                //取消注册
                key.cancel();
                //关闭通道
                channel.close();
            } catch (IOException e2) {
                e2.printStackTrace();
            }
        }
    }

    //转发消息给其它客户(通道)
    private void sendInfoToOtherClients(String msg, SocketChannel self) throws IOException {

        System.out.println("服务器转发消息中...");
        System.out.println("服务器转发数据给客户端线程: " + Thread.currentThread().getName());
        //遍历 所有注册到selector 上的 SocketChannel,并排除 self
        for (SelectionKey key : selector.keys()) {

            //通过 key  取出对应的 SocketChannel
            Channel targetChannel = key.channel();

            //排除自己
            if (targetChannel instanceof SocketChannel && targetChannel != self) {

                //转型
                SocketChannel dest = (SocketChannel) targetChannel;
                //将msg 存储到buffer
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                //将buffer 的数据写入 通道
                dest.write(buffer);
            }
        }

    }

    public static void main(String[] args) throws IOException {
        //创建服务器对象
        Server groupChatServer = new Server();
        groupChatServer.listen();
    }
}